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Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse event rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of any other drug and may not reflect the rates observed in practice.

The safety of DIFICID 200 mg tablets taken twice a day for 10 days was evaluated in 564 patients with CDAD in two active-comparator controlled trials with 86.7% of patients receiving a full course of treatment.

Thirty-three patients receiving DIFICID (5.9%) withdrew from trials as a result of adverse reactions (AR). The types of AR resulting in withdrawal from the study varied considerably. Vomiting was the primary adverse reaction leading to discontinuation of dosing; this occurred at an incidence of 0.5% in both the fidaxomicin and vancomycin patients in Phase 3 studies.

Table 1: Selected Adverse Reactions with an Incidence of ≥ 2% Reported in DIFICID Patients in Controlled Trials

  DIFICID (N=564) Vancomycin (N=583)
System Organ Class Preferred Term n (%) n (%)
Blood and Lymphatic System Disorders
  Anemia 14 (2%) 12 (2%)
  Neutropenia 14 (2%) 6 (1%)
Gastrointestinal Disorders
  Nausea 62 (11%) 66 (11%)
  Vomiting 41 (7%) 37 (6%)
  Abdominal Pain 33 (6%) 23 (4%)
  Gastrointestinal Hemorrhage 20 (4%) 12 (2%)

The following adverse reactions were reported in < 2% of patients taking DIFICID tablets in controlled trials:

Gastrointestinal Disorders: abdominal distension, abdominal tenderness, dyspepsia, dysphagia, flatulence, intestinal obstruction, megacolon

Investigations: increased blood alkaline phosphatase, decreased blood bicarbonate, increased hepatic enzymes, decreased platelet count

Metabolism and Nutrition Disorders: hyperglycemia, metabolic acidosis

Skin and Subcutaneous Tissue Disorders: drug eruption, pruritus, rash

Post Marketing Experience

Adverse reactions reported in the post marketing setting arise from a population of unknown size and are voluntary in nature. As such, reliability in estimating their frequency or in establishing a causal relationship to drug exposure is not always possible.

Hypersensitivity reactions (dyspnea, angioedema, rash, and pruritus) have been reported.